Spray-drying large volumes (i.e., thousands of pounds per hour) of detergent slurries in a spray-drying tower is a complex procedure involving numerous interrelated factors such as volume and rate of production, slurry ingredients, processing requirements and conditions, massive requirements of drying air, and the desired physical and performance properties of the spray-dried product.
Spray towers have been used employing a single level of atomizing nozzles which are located near the top of the spray-drying chamber. Such spray-drying methods and apparatus are disclosed in U.S. Pat. No. 2,851,097, Ledgett, issued Sept. 9, 1958.
U.S. Pat. Nos. 3,629,951 and 3,629,955, both issued Dec. 28, 1971 to Davis, Hanes and Sagel, disclose granular detergent compositions made by an improved multi-level spray-drying process and apparatus.
U.S. Pat. No. 4,261,793, Nakamura et al, issued Apr. 14, 1981, discloses countercurrently spray-drying a detergent slurry using at least two different levels of uniformly spaced atomizing nozzles.
U.S. Pat. No. 3,519,054, Cavataio et al, issued July 7, 1970, discloses multi-colored granular detergent compositions made by spraying two liquid streams downwardly in a spray tower, one stream being sprayed from a level 15 to 60% below the other, into an upwardly flowing stream of gas.